Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 250629

1100 PM PDT TUE MAY 24 2016

New Aviation Discussion


Low pressure will move across the area tonight and tomorrow,
resulting in cool weather and a slight chance of showers and
thunderstorms, mainly for the mountains and some interior areas.
Warming is expected late this week as the main upper low moves
east, but temperatures will remain near or slightly below normal
through early next week as a weak trough lingers over the area.



An upper low spinning a few hundred miles off the Central Coast this
evening was helping to bring varying amounts of mainly stratocu to
the mtns and some cst and vly areas. There were a few light showers
in the VTU County mtns late this afternoon, otherwise dry conditions
prevailed across the region into the evening hours. However, with the
upper low forecast to move close to the s SBA County coast late
tonight, and a cyclonic flow aloft combined with a persistent lower
level moist layer, there will be the possibility of a few showers
developing over interior areas of SLO/SBA Counties and mainly over
the nrn mtns of VTU/L.A. Counties overnight. Even isolated drizzle
cannot be ruled out for coastal and vly areas s of Pt Conception.
Otherwise, partly to mostly cloudy skies will prevail for much of
the region thru the night. Areas of gusty s to w winds in the mtns
and deserts this evening will diminish some overnight.

The upper level low is forecast to slide e across VTU and L.A.
Counties thru the day on Wed, then track further e into AZ for Wed
night. A broad mainly nw flow aloft will prevail over swrn CA Thu
thru Fri with slowly rising 500 mb heights.

A slight chance to chance of showers can be expected over much of
the forecast area Wed morning due to the influence of the upper low
on the deep moist layer. A slight chance of showers and
thunderstorms will affect interior portions of SLO/SBA/VTU/L.A.
Counties for Wed afternoon, including the mtns and deserts, thanks
to some lingering instability and a piece of energy sliding down the
back side of the upper low. Overall, though, it looks like partly to
mostly cloudy skies and cool conditions can be expected across the
region. increasing onshore gradients will help to bring even
stronger winds to the Antelope Vly Wed afternoon and evening,
possibly reaching advisory levels. Gusty sw to nw winds will also
affect the Central Coast, foothills and mtns Wed afternoon and early

More extensive night and morning low clouds and fog are forecast for
the Central Coast and Santa Ynez Vly with varying amounts of clouds
over the coast and vlys of VTU/L.A. Counties. The marine layer
pattern should affect all the coast and adjacent vlys Thu night into
Fri morning, with an eddy helping to enhance the marine layer clouds
s of Pt Conception. Otherwise, partly cloudy skies can be expected
Thu night, with mostly sunny skies developing in all areas by early
Fri afternoon. Good onshore flow will prevail each day, with gusty
sw to nw winds from the Central Coast to the foothills, mtns and
deserts from the afternoon to evening hours. Gusty nw to n canyon
winds are also expected along the SBA s coast and mtns each evening.
However, it looks like winds should be mostly sub-advisory for Thu
and Fri.

Temps across the region will be 5 to 15 deg below normal on Wed,
then warm to near normal to slightly below normal for most areas by



Extended models showing weak upper level trough across California
over the weekend, with continued strong onshore flow near the
surface. This will maintain mild temperatures, along with night
and morning marine layer clouds, and gusty onshore winds in the
mountains and deserts. Some weak upper level ridging expected to
follow Monday into Tuesday, leading to a few degrees of warming
across interior areas.




At 0530Z at KLAX...There was a 2500 foot deep marine layer. There
was a weak inversion above the marine layer with a top of 3400 feet
and a temperature of 10 degrees celsius,

Low confidence in all coast and vly TAFs. There are three
different cloud layers (low MVFR, high MVFR and low VFR) that will
move in and out over the TAF sites through the early morning hours.
Better confidence that most sites will have a high MVFR cig after
sunrise with a slow transition to a low VFR cig late in the morning
or early afternoon.

KLAX...Low confidence in TAF. Cigs of 015 025 and 035 or no cig at
all are equally possible overnight. There is a 30 percent chc of
BKN015 aft 14Z and a 30 percent chc of BKN025 aft 20Z.

KBUR...Low confidence in TAF. Cigs of 015 025 and 035 or no cig at
all are equally possible overnight. There is a 30 percent chc of
BKN025 aft 18Z.



24/800 PM

Mainly light winds and small seas are expected through Wednesday
morning, with no SCA concerns. There is a high probability that
Small Craft winds will develop across the outer waters Wednesday
afternoon through at least Friday morning, and possibly through
the weekend. Models indicate a chance of gale force gusts over the
outer waters Saturday and Sunday. There is also a good chance
that SCA level wind gusts will affect the western portion of the
Santa Barbara Channel Wednesday afternoon through Wednesday night,
and again Thursday afternoon and evening. 40 percent chance that
the NW portion of PZZ655 near Anacapa Island will meet SCA
criteria as well Wednesday evening into early Thursday morning.

A Catalina Eddy will likely spin up during morning hours
Thursday through Sunday across the inner waters within the SoCal





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